In IEEE (Institute of Electrical and Electronics Engineers) 802.11, a new project team ISD (infrastructure service discovery) was established by RIM (research in motion) Company in November, 2011. The main aim of this project team is to research how an STA (station) discovers infrastructure service information and how an AP (access point) of a network side informs the STA of its own service information under the condition that no initial connection is established between the STA and the AP.
Since the project is being at a research stage, only application scenarios and demands are proposed, but substantial solutions are not proposed, the present invention proposes a solution, that is, the AP broadcasts an index message of its service information and appearance time of a specific message of the index message in a Beacon frame. Considering that the detailed information of the infrastructure service information should be very long, an infrastructure service information discovery (ISD) message may not include all the detailed information but only include the detailed information of a catalogue index, and then the following problems are caused.
1. If the broadcast message only includes the detailed information of a catalogue index, the STA may not receive a catalogue index message broadcasted by the AP previously, that is, a Beacon frame, but only receives the broadcast message; if the broadcast message does not include the detailed information which the STA wants to learn after analyzing, the STA must wait till receiving the infrastructure service information to be learnt; since the time point information of the detailed infrastructure service information to be learnt is not received previously, this period of time is unknown, that is to say, the STA must be kept in a wake-up state in this period of time; whether each received broadcast message is the desired infrastructure service information is judged by analyzing; and due to massive analyzing operation and waiting time, the STA would consume a large amount of power, which is not favorable for power saving of the STA.2. For those STAs which do not need to learn the infrastructure service information provided by the AP but receive this ISD broadcast message, the STAs may carry out other services with the AP, e.g. surfing the Internet and the like. Each STA needs to wait for next Beacon frame to continue a service and may not judge how many ISD broadcast messages are needed before the Beacon frame appears in addition to this broadcast message from this ISD message, the STA must receive and analyze each ISD message in this period of time, and a large amount of power is consumed during analyzing and other operations of these ISD messages, which is not favorable for power saving of a terminal; or, if the ISD message received by the STA includes all service information of the AP, the message is very long, and if the STA may not judge whether this message is an ISD message from a physical frame header of this ISD message, the STA must receive and analyze the whole ISD message, and the STA would consume a large amount of power in the processing process, which is not favorable for power saving of the STA.
Therefore, to solve the above problems and ensure that the STA does not excessively consume power at the same time, a new technical scheme needs to be proposed, so that after the STA receives the broadcast message of the AP, the STA may judge the type of the received broadcast message from a physical frame header or an MAC frame header of the broadcast message, may judge whether this broadcast message is the desired information according to the type of the broadcast message and does not need to receive all broadcast messages for analyzing, which is favorable for power saving of the STA.